The present invention relates to a technique for recording data that is associated to other data held in a storage medium. More particularly the present invention relates to a technique for reducing the volume of data in the storage medium.
Conventionally, to edit video or audio recorded by, for example, a video tape recorder VTR camera, video and audio data must first be recorded from the original video tape to a randomly accessible medium in a computer, such as a hard disk or DVD, and editing performed on this data using various applications.
The following is an explanation of the conventional editing methods for video data and audio data, with editing on a personal computer as an example.
Seen from the standpoint of data editing, the personal computer uses a) an interface unit, for receiving video data and audio data from outside, b) a storage unit, comprising a hard disk or the like for holding video data and audio data, c) a data holding unit, for holding video data and audio data received from the interface unit in the storage unit, d) a data obtaining unit, for obtaining data to be reproduced from the storage unit, e) a cathode ray table (CRT) for displaying video data obtained by the data obtaining unit, and f) a speaker for outputting audio data obtained by the data obtaining unit.
(1) Operation of each unit involved in recording video data and audio data.
The interface unit receives video data and audio data from outside and outputs them to the data holding unit.
The data holding unit, upon receiving video data and audio data, performs analog to digital conversion and assigns a unique pathname to each data. Each path name comprises a file name (e.g., xe2x80x9cMOV0002xe2x80x9d and xe2x80x9cAUD0002xe2x80x9d), which includes two codes, (a) a four-digit number associating the video and audio data as a set (e.g., xe2x80x9c0002xe2x80x9d), and (b) letters classifying the data as video or audio (e.g., xe2x80x9cMOVxe2x80x9d for video and xe2x80x9cAUDxe2x80x9d for audio). The path names are stored in the storage unit and mapped in the management file xe2x80x9cLIST_MGRxe2x80x9d in the xe2x80x9cMGR_INFOxe2x80x9d directory of the storage unit.
The management file xe2x80x9cLIST_MGRxe2x80x9d holds index data, which shows association of the data held in the storage unit to data generated by editing.
(2) Operation of each unit involved in normal reproduction.
The data obtaining unit obtains the path name, e.g., a path name including xe2x80x9cMOV0002xe2x80x9d or xe2x80x9cAUD0002xe2x80x9d, of data to be reproduced from the management file xe2x80x9cLIST_MGR,xe2x80x9d obtains the video data and audio data associated with the path name, performs digital to analog conversion, and outputs the video data and audio data to the CRT and speaker, respectively, in parallel.
The CRT and speaker output, respectively, the video and audio represented by the data received from the data obtaining unit.
(3) Operation of each unit involved in data editing.
The following explanation uses an example of data editing involving after-recording, wherein music, narration or other audio is substituted for the audio data which was recorded and is held together with the video data in the storage unit.
When after-recording editing is performed, the data holding unit receives the music, narration or other audio data from the interface unit, converts the data from analog to digital form, and designates a path name (hereinafter xe2x80x9cafter-recording path namexe2x80x9d), including a file name (e.g., xe2x80x9cAUD0006xe2x80x9d, wherein xe2x80x9cAUDxe2x80x9d indicates audio data). The data holding unit then stores the after-recording path name in the storage unit, and maps the after-recording path name to the to-be-edited video data and audio data in the xe2x80x9cLIST_MGRxe2x80x9d management file.
When data is to be reproduced, the data obtaining unit refers to the index data in the xe2x80x9cLIST_MGRxe2x80x9d management file to determine if the data to be reproduced has been after-edited. When association to an after-recording path name is found, the data obtaining unit obtains (a) the video data, and (b) the audio data which is associated with the video data and has an after-recording pathname. The data obtaining unit converts these data from digital to analog, and sends them to the CRT and speaker.
The CRT and speaker receive, respectively, the video data and audio data from the data obtaining unit and output video and audio.
FIG. 1 shows the logical structure of the data in the storage unit, in a case where conventional after-recording editing has been performed.
Data files holding video data and audio data are stored under a directory that has xe2x80x9cPRGxe2x80x9d followed by a four-digit number in its name (for example, xe2x80x9cPRG0001xe2x80x9d in the path name xe2x80x9cD:¥PRG0001¥MOV001.MODxe2x80x9d in FIG. 1).
Recently, VTR cameras, mobile telephones, mobile music players and other portable devices use as a storage unit next-generation memory cards, such as SD (secure digital) cards, which are lightweight and removable/exchangeable.
These next-generation memory cards use the same storage configuration, i.e., a hierarchy of directories and files, as computer operating systems. Although their data capacity (around 64 megabytes) is small compared with a personal computer""s hard disk, the easy exchange of data among these portable devices and with personal computers accounts for the high interest shown in the cards.
By connecting a memory card to the above computer interface unit, data editing is easily accomplished. In addition, some types of portable devices are equipped with functional units similar to a computer, including a storage unit, a data holding unit, and a data obtaining unit, allowing data editing on the portable device.
However, this conventional technology is accompanied by the following problem. As data editing, such as after-recording, is performed on the portable device, the volume of the management file in the memory card swells, creating stress on the limited memory capacity of the card.
It is therefore an objective of the present invention to provide, for a device with limited memory, (1) a data obtaining apparatus and a data holding apparatus, which limit the increase in data volume due to data editing, (2) a storage medium, which can store the same data as the prior art but more compactly, (3) a data obtaining method, for retrieving data from the storage medium, and (4) a data holding method, for storing data in the storage medium.
In order to achieve the stated objective, the present invention includes a storage medium storing one or more data files and address information showing a path of each data file, characterized in that the address information is denoted as a numerical value, which is derived from a given partial notation of a name of the path, and a data size of the numerical value is smaller than a data size of a character string denoting the same address information.
By using short numerical notations, the size of the data is reduced, saving storage capacity in the memory card.
Further, when the storage medium may store a plurality of data files, which are assigned to a plurality of groups, the path name may include a type 1 notation identifying a group and a type 2 notation identifying a data file within the group, the partial notation may include the type 1 notation, and the path name may be derived from the numerical value by a given reversible operation.
With this arrangement, the original path name can be found from the partial notation, by reversing the operation.
Additionally, when a group includes a plurality of data files that hold different kinds of data, the type 2 notation may indicate which kind of data.
With this construction, even data of different kinds can be converted into the same notation, in the case where both path names include the same type 1 notation, i.e., both sets of data belong to the same group.
Additionally, the kinds of data may be video and audio.
With this construction, video data and audio data belonging to the same group can be converted into the same notation.
Additionally, the storage medium, when a group includes a first audio data file and a first video data file, and a second audio data file is associated to the group, may store a first numerical value, derived from the path names of the first audio data file and the first video data file by the given reversible operation, with an added flag showing the association of the second audio data file, and the path name of the second audio file may be derived by adding a given notation to the first numerical value.
With this construction, address information for the first audio data file and first video data file, which are assigned to the same group, as well as for the second audio data file, which is associated to the other two data files, can all be generated from the above numerical value.
Additionally, when a group includes a first audio data file and a first video data file, and a second audio data file is associated to the group, the storage medium may store a first numerical value, which is derived from the path names of the first audio data file and the first video data file by the given operation, and a second numerical value, which is derived from the path name of the second audio data file by the given operation and associated to the first numerical value.
With this construction, address information for the first audio data file and the first video data file can be generated from the above first numerical value. Also, address information for the second audio data file, which is associated to the other two data files, can be generated from the second numerical value. This allows a reduction in data volume as compared with storing the original path name.
Additionally, data in the first audio data file and data in the first video data file may be recorded in parallel, and the data in the second audio data file may be after-recording data to replace the data in the first audio data file.
With this construction, the volume of data for associating the after-recording data to the video data can be reduced.
Additionally, when the path name is composed of a string of characters, and a character representing a base n number (where n is an integer greater than one) is included in the given partial notation in the string, the given reversible operation may convert the character into a base n numerical value (where n is an integer greater than one).
With this construction, the above given operation can be performed by a simple mathematical operation, simplifying the structure of the processing apparatus.
Additionally, the data files may be stored in logically hierarchical locations; each path name may include a name of a directory, which indicates a location in the hierarchy and contains a plurality of data files, and a group name, which indicates the group; the given partial notations may be characters corresponding to the notations showing the base n numbers (where n is an integer greater than one) of the directory names and group names; and the given operation may link the two numerical values obtained by the conversion performed on the characters from the directory name and group name of each path name.
With this construction, address information showing the directory name and group name can be generated from the above numerical values.
Additionally, the base n number may be a hexadecimal number.
With this construction, the space needed for storing the above numerical values can be reduced, reducing the memory capacity of the storage medium.
Additionally, a data obtaining apparatus according to the present invention, which retrieves a desired data file from the storage medium, is characterized by (1) a numerical value designating unit, which designates, from among a plurality of numerical values held in the storage medium, a numerical value corresponding to a data file to be retrieved; (2) a path name generating unit, which generates a path name for a given character string, by performing a given operation to combine a given character string with a character string converted from a numerical value that is designated by the numerical value designating unit; and (3) an obtaining unit, which, if there is a data file with a path name generated by the path name generating unit in the storage medium, retrieves the data file. Similarly, a data obtaining method of the present invention, for retrieving a desired data file from the storage medium, is characterized by: (1) a numerical value designating step, in which a numerical value, from among a plurality of numerical values stored in the storage medium, is designated as corresponding to a data file to be retrieved; (2) a path name generating step, in which a path name is generated for the given character string, by performing a given operation to combine a given character string with the character string that is converted from a numerical value designated in the numerical value designating step for the character string; and (3) an obtaining step, in which, if there is a data file with a path name generated by the path name generating unit in the storage medium, the data file is retrieved.
With this construction, using a numerical value whose data size is smaller than that of the path name, the path name of the data file to be obtained can be generated, and the data file can be retrieved, if it exists.
Additionally, the path name generating unit may generate a path name for each of the plurality of different given character strings.
With this construction, a plurality of path names can be generated from one numerical value stored in the storage medium, and a plurality of data files can be retrieved, thereby reducing the volume of data stored in the storage medium compared with storing a plurality of path names as character strings.
Additionally, a numerical value designated by the numerical value designating unit may be a base n numerical value (where n is an integer greater than one), and the given operation may perform the combination by inserting a character corresponding to the numerical value into each given position in the given generated character string.
With this construction, because the generated path name includes characters for the numerical values stored in the storage medium, the relationship between the path name and the numerical value can be easily inferred from their notations.
Additionally, the numerical value designating unit, when a first numerical value, one of a plurality held in the storage medium, is associated to a distinct second numerical value, may designate the first and second numerical values as corresponding to a data file to be retrieved, and the obtaining unit may retrieve a data file whose path name is generated from the second numerical value and includes a given first character string, in place of a data file whose path name is generated from a first numerical value and includes a given first character string.
With this construction, because associative information is stored as numerical values, whose data size is small, the volume of data stored in the storage medium can be reduced, as compared with association by path names.
Additionally, a flag showing a first value or a distinct second value may be attached to a numerical value held in the storage medium; a plurality of character strings generated by the path name generating unit may include a first character string; the path name generating unit, when the flag that is attached to the numerical value designated by the numerical value designating unit is the second value, may generate a second character string, distinct from the first character string; and the obtaining unit may retrieve a data file whose path name includes the given second character string, in place of a data file whose path name includes the first character string.
With this construction, association is made by a flag attached to the numerical value, whose data size is small, reducing the volume of data to be stored in the storage medium as compared with making association by path names.
Additionally, the second character string may be the first character string with one or more given characters deleted or changed.
With this construction, the relationship between the path name and the numerical value is easily deduced from their notations.
Additionally, the data holding apparatus of the present invention, of a type which has a data obtaining unit for retrieving data files and a path allocating unit for generating and allocating a path name for a retrieved data file and which stores a data file in a storage medium, is characterized by: (1) a numerical value generating unit, which performs a given operation to generate, as address information corresponding to the path name, a numerical value, whose data size is smaller than that of the path name, from a given partial notation that is part of the path name; and (2) a holding unit, which stores the numerical value and the data file, associated to the path name identifying a location of each data file in the storage medium. Similarly, a data holding method of the present invention, of a type which has a data obtaining step for retrieving data files and a path allocating step for generating and allocating a path name for a retrieved data file and which stores a data file in a storage medium, is characterized by: (1) a numerical value generating step, in which a numerical value, whose data size is smaller than that of the path name, is generated, as address information corresponding to the path name, from a given partial notation that is part of the path name; and (2) a holding step, in which the numerical value and the data file are stored in the storage medium, associated to the path name identifying a location of the data file in the storage medium.
With this construction, address information corresponding to the path name is stored in the storage medium as numerical values, whose data size is smaller than the original path names, resulting in a reduction in the volume of data in the storage medium.
Additionally, the path allocating unit may link two character strings showing a directory name and a file name that are used for data management, to generate the path name of the retrieved data file; the character string showing the directory name may be composed of a unique character string and a base n (where n is an integer greater than one) first numeral string; the character string showing the file name may be composed of a given character string, which shows the type of file, and a base n (where n is an integer greater than one) second numeral string; and the numerical value generating unit may generate the numerical values by using the first and second numeral strings as the given partial notation and linking the numerical values obtained therefrom.
With this construction, the numerical value generated as address information bears closer resemblance to the path name.